Pool Info: Pool Pumps & Motor Information

Swimming Pool Filter pumps

The heart of your circulation system, your pool pump pulls water from one or more suction ports (skimmers and main drain), and pushes it through the filtering, heating and sanitizing equipment, and back to the pool through the wall or floor returns, pressure cleaners or water features.

The pool pump has the most important job on the pool equipment pad, because when the pump is not working, nothing else works either.

How do I know what pump is right for my pool?

Contrary to selecting a pool filter, a bigger pump is not always a good thing. Unless you have been advised by a pool professional, or are otherwise certain that your existing pump was undersized, it would be wise to keep the same horsepower as you have now.

Different pumps produce different flow rates, even if they are the same horsepower. A 1hp Hayward pool pump will not produce the same flow rate as a 1hp Pentair pool pump. More important than matching pump horsepower, is matching pump flow rates. For instance, a 1hp Hayward Superpump is capable of 75 gpm, but a 1hp Pentair Whisperflo is capable of 115 gpm. This does not make the Pentair pump a ‘better’ pool pump, on the contrary, flow rates that are too high can damage your filter and piping, and result in ineffective filtration.

If the existing pump has done you well, it is easiest to replace a failed pool pump with the exact same make/model/size of pump. The height and length is also the same, which makes the plumbing job much easier. A different pump will usually require some adjustment to fit the pipes to the height of the front inlet and the length to the back discharge port. Dimensions of most pumps can be found on any specific pump’s product page, and some do match up, for instance Pentair SuperFlo matches up to Hayward Superpump, or the Hayward Superpump VS pumps, and Whisperflo pumps can be swapped out with Pentair Intelliflo VS pumps.

How do I know what Horsepower my pump motor is?

The horsepower should be listed on the nameplate (left) of the pump motor (in very tiny letters - hp). If the motor nameplate is burnt or worn off, a printed part number from the impeller can tell us which hp pump motor you have. This is because different horsepower pool pumps use different impellers. A motor manufacturer motor model number listed on the label can also be cross referenced with a quick online search.

Selecting a New Pool Pump

When buying a swimming pool pump, look for and buy a pool pump made by a major manufacturers; that is, Hayward, Jacuzzi, Pentair (American, Pac-Fab, Purex, Sta-Rite) and Waterway - well known market leaders. Other pumps of less recognizable brands are likely imported knock-offs of dubious quality, with non-existent replacement pump parts availability.

Remember that all pool pumps are different in hydraulics, shape, basket, lid, and colors. However, these may or may not matter a whole lot. Read on for more substantial ways to discern between filter pumps.

You will find that there are low head pumps for aboveground pools and medium and high head pumps for inground pools. The term "head" refers to the flow rate, in a backwards kind of way.

Above ground filter systems usually use a Low Head pump like a Dynamo, Hi-Flo or Power-Flo. Not self-priming, these are installed below water level.

Pools over 25,000 gals could possibly use the High Head pumps like, Super II, Challenger, or the Whisper-Flo, with large enough plumbing and filter size.

The motors used on pool pumps are all nearly the same, most made by AO Smith, Century or Emerson. There have been many innovations in pump technology in the recent years, with the most notable being Variable Speed pumps, which use a completely different motor type.

For Variable Speed pumps to work well, you want to be able to use all speeds, and if you oversize a VS pump to your pool plumbing and filter size, it can cause problems. Fortunately, there are smaller medium head VS pumps, as well as larger high head VS pumps.

Larger pools, or pool/spa combos and pools with water features can use a high head VS pump, like the Ecostar or the IntelliFlo.

Remember when selecting a new pump to match hp, and pump type and flow rates. Use the Pump Flow Rate Charts, (see below) also known as Performance Data. This is based on a sample ‘feet of head’ of 30 or 40 feet. This is the only true way to compare pool pumps to each other.

How much Head or Resistance is in your system? That’s hard to calculate without a lot of math, but to compute resistance as measured in feet of head, you would need to know the resistance value of each length of pipe, every plumbing fitting, valve, pump, filter, heater, etc. But let’s keep this simple, shall we? If your pool plumbing is very simple, and your pump is fairly close to the pool, you may have 20-30 feet of head overall. If you have 3 or 4 lines coming into the pump, a large filter and maybe a heater, you may have 30-40 feet of head overall. If your pool is quite complicated, with lots of large pipes and extra equipment or water features, with a filter tucked away far from the pool, you may have 40-50 ft of head overall. If you can find the original info from the pool builder, the total resistance may be listed on the spec sheet.

As Americans, it's natural to want the big V-8 power plant, but a pump that is too powerful could actually prevent filtration while damaging the filter and heater. Pipes or fittings can separate, filter internals can collapse, and heaters can be stripped of copper.

When matching pumps to filters, check the Design Flow Rate of the filter on the filter label. The average flow for the pump you select (at a given level of resistance) should be within 10% of the pool filter's Design Flow Rate.

Remember also, that a smaller hp motor is going to draw fewer amps, which is going to cost less to operate. If you are careful to match up flow charts, you could actually reduce the hp required, while increasing the head of the pump. For instance, a 1/2 hp Whisperflo produces about the same amount of flow as a 1-1/2 hp SuperPump, at a given resistance, or head. So, you could replace a Super Pump with a smaller Whisperflo pump; reducing your amp draw and cutting electrical expense in half.

When selecting a new pool pump, if you aren’t buying the same make/model, keep it close to the original specifications, and use the Pump Flow Charts. Most systems could handle a small increase in pump size, especially if you are replacing the filter with a larger one, but be careful to match pump flow rate with your filter’s design flow rate. And remember that the flow charts are assuming a clean filter, when in reality, your overall system resistance will increase as the filter pressure rises.

How do pool pumps work?

The water is pulled from the pool by a brass or plastic impeller that is shaft driven by an electric pump motor. On the way to the pump, the water is under a vacuum, which creates the suction. After the water leaves the impeller, the water is put under pressure, being pushed until it is released into the pool. The design of the impeller and impeller housing creates the suction required to lift water, and the pressure to force it through the filter. An air tight suction side is necessary (without air leaks) to create the vacuum to pull the water from the pool.

The electric motor is powered from a breaker on your electric panel (or fuse box), at 115 or 230 volts. Usually motors over 2 hp need 230V power to operate, and most smaller hp pumps convert to accept either 115 or 230 volts. Above ground pumps are often 115V only, and have a pump power cord for GFCI outlet power.

Electrical consumption will vary by pump, and manufacturers have been designing motors and pumps (the wet end) which are more efficient and consume much less energy than older pumps. Energy efficient motors draw fewer amps; the smaller the amperage draw of the motor, the less expensive it is to operate. On motors with reversible voltage (115V/230V), Amps is listed on a motor nameplate with two numbers, i.e. 16/8. The first number refers to the amps used to start the pump with 115V, and the lower number is when the motor is wired with 230V.

How long do motors last?

Pool pump motors typically last about 8-10 years before needing either rebuilding or replacing. Noisy, screeching front and/ or rear bearings will let you know when you need to do something. Read below for more information on noisy pool pumps.

Many people replace the entire pool pump, when only the motor is bad. The plastic parts of the pool pump, the front half, known as the wet end, do not generally wear-out or fail, and could last for the life of the pool, with an occasional replacement of small parts like the basket, pump lid o-ring or drain plugs.

Rebuilding a motor is a replacement of the bearings and shaft seal, which could be a wise direction if the motor is only a few years old. Pool pump motor bearings are sealed, and do not require lubrication or maintenance. There are several sizes of bearings and seals, with different motors using different sizes.

Pump motors are built for continuous duty, in the outdoors, but will last longer if shielded from weather and excess moisture. Removing a pump for winter storage can prevent the rust that develops between the stator and rotor on pumps left outside during periods of non-use.

Pool Pump Troubleshooting Guide: A guide to help you with some of the most common problems that can occur with pool pumps.

Leaking pump?

A very common problem is the threaded fitting carrying water out of the pump shrinking from heat and allowing water to drip, run and then spray. This can be replaced with a high temp fitting to prevent its reoccurrence. You’ll need to cut the pipe after the pump, replace the MTA (male threaded adapter) using an appropriate thread sealant, and reconnect the fitting to the pipe using some new pipe and a coupling or union.

Water may also leak from a worn out mechanical shaft seal. The pump seal is the separation between the wet end and the dry end (motor) of the pump, and allows the motor shaft to enter the pump, and spin freely without leaking water. Ozone and Salt resistant pump seals are made with materials that can better resist deterioration from salt water or ozone introduced in front of the pump.

A blown shaft seal is evident from water dripping down the back of the seal plate, and onto the ground, but should be distinguished from a leaking pipe fitting as described above or a leaking clamp band which holds the seal plate to the volute, or impeller housing. These leaks can also drip directly off the bottom of the pump, mimicking a leaking shaft seal.

Air in pump basket?

The pump is meant to operate air free, to create the necessary vacuum. After some time, you may notice air in the pump basket, especially if you have a clear lid to observe such things. Air in the pump will reduce filtering efficiency, allow dangerous air to build up in filter, and can prevent your pump from catching prime (being able to move water).

The problem is usually found in front of the pump, above-ground. Rarely do we have to look underground for the source of the air. The most common cause is the pump inlet fitting being loose, usually shrunken slightly from heat, or installed without thread sealant.

Air in the pump basket can be caused by something as simple as the water level being too low in the pool. Also, if the skimmer weir is stuck in the up position, it will block the water and cause the skimmer to drain and take in air. Also check that the pump basket lid is secured very tightly and the o-ring is lubricated with Teflon lube. Drain plugs without Teflon tape, or missing an o-ring (used on some pumps) will also cause the pump to draw air.

Locating an Air Leak

Make sure the strainer lid is on tight, with a clean, lubed o-ring. Also check that all drain plugs are tight. This void will always be before the impeller. After the impeller is what we call "the pressure side". Any leak or void after the impeller will leak water out. Any leak or void prior to the impeller (in front of the pump impeller) will draw air in when the pump is on. A pool pump will "pump" air if it can; it is the path of least resistance. So, your system needs to be almost airtight to run properly.

A good trick in locating an air leak is to shut off the motor when it's under full pumping head pressure, and look for water to spray back out of the void where the air was entering. You have to be quick to catch this spray-back, looking closely. If that didn't work, you can buy a Drain King at your local hardware store. This connects to a garden hose and puts the line under pressure. Push the Drain King into the skimmer, and close off other suction lines (skimmer and main drain valves). Remove the pump lid and use a plug or hold a tennis ball to plug up the pump entrance. Turn on the garden hose to allow pressure to build up in the lines before the pump basket and squirt out (or drip) at the source of the leak. You can also put the multiport valve on the Closed position, or close return side valves and pressure test the entire system in this way. If you find water leaking anywhere before the pump discharge pipe, that is the source of the air.

Make sure the water level in the pool is high enough, and that the skimmer weir is not stuck in the up position. Check that the incoming and outgoing valves are in the open position. If you suspect a clogged line, you can also use a Drain King to pressurize the line backwards from the skimmer towards the pump and remove leaf/debris obstructions.

Pump is not pumping water like usual?

If it’s not an air leak, (see above) it’s probably an obstruction. Could be a dirty pool filter, or closed valves. Check your skimmer baskets for heavy debris. Make sure the pump basket is clean and properly positioned, and that the pump lid is on very tight. Some types of pumps have a pump strainer basket that locks into place to prevent the basket from floating and blocking the entrance, or allowing debris to bypass the basket, and a clogged impeller.

When the pump basket is cracked it can also allow debris to clog the pump's impeller. If the pump basket is cracked or damaged, it should be replaced. To check the impeller, turn off the motor, remove the pump basket and reach into the volute and feel if it is clogged with debris. If you cannot feel for sure, you may need to remove the motor from the pump to properly inspect the impeller. Many times you need only remove a clamp band or 4 to 6 nuts, to separate the motor from the pump.